Double acting fluid cylinder

ABSTRACT

A piston and cylinder are provided wherein the piston has driving movement in both directions and instead of having the usual piston rod it has an arm projecting through a slot in the cylinder. Such slot is sealed off by a flexible strip anchored at the ends of the cylinder and having tension means acting thereon to maintain it in a tight condition for effective sealing. The cylinder of the invention has efficient usage as the drive means for truck cab windows and utilizes an extruded cylinder portion of minimum dimension particularly applicable for installation in truck doors to drive the windows.

United States Patent 1191 1111 3,893,378 Hewitt July 8, 1975 [54] DOUBLE ACTING FLUID CYLINDER 3,414,316 12/1968 Williams et 74/566 X ,549,244 12 1970 Sh fi' 67 6O [76] lnventor: Delbert c. Hewitt, 522 SE. Alder, 3 a 2 x Portland, Oreg. 97214 FOREIGN PATENTS OR APPLICATIONS [22] Filed: No 23, 1973 386,565 1/1933 United Kingdom 220/215 PP N05 418,564 Primary Examiner-Irwin C, Cohen Attorney, Agent, or Firm-Eugene M. Eckelman [52] US. Cl 92/88; 92/169 [51 1m. 0...... F16] 13/02; F16j 15/16; Fl6j 15/50 STRACT Field Of ch 5, 169; 220/ -5; A piston and cylinder are provided wherein the piston 160 has driving movement in both directions and instead of having the usual piston rod it has an arm projecting [56] Referenc s C ted through a slot in the cylinder. Such slot is sealed off by UNITED STATES PATENTS a flexible strip anchored at the ends of the cylinder 1 431,084 10/1922 Anglemyer 74/566 x and having mush" means acting thew)" maintain 903,153 3I|933 cordreym n 220/245 it in a tight condition for effective sealing. The cylin- 2,200,427 5/1940 Merz 92/88 x der f th inv ntion has efficient usage as the drive 2,473,430 6/1949 Hoffar 92/88 means for truck cab windows and utilizes an extruded 2,686,497 8/1954 Dodley 92/88 cylinder ortion of minimum dimension particularly Andrus X applicable for installation in truck doors to drive the 3,143,181 8/1964 Bays et al.. 92/35 x windows 3,221,610 12/1955 King et al. 92/88 X 3,278,153 10/1966 Dallas 267/160 X 4 Claims, 11 Drawing Figures SHEET @NFHTFMUL 8 I975 DOUBLE ACTING FLUID CYLINDER BACKGROUND OF THE INVENTION This invention relates to new and useful improvements in double acting fluid cylinders.

Prior art devices have heretofore been proposed wherein double acting cylinders are constructed of a slidable piston which instead of utilizing an axially extending piston rod utilizes a laterally projecting drive arm which extends through a longitudinal slot in the side of the cylinder. These structures have the advantage that they require a minimum of length dimension in the mounting area therefor. Such a device is shown in US. Pat. No. 3,221,610 of which the present applicant is a joint patentee. In such prior art structure, side sealing means is required since the drive arm connected to the piston projects through the side of the cylinder. Such sealing means of the prior art often becomes defective after a period of use of the cylinder due to the wearing or strain on the parts.

SUMMARY OF THE INVENTION According to the present invention and forming a primary objective thereof, a double acting fluid cylinder is provided which has a laterally projecting drive arm on the piston instead of the usual axial piston rod extending through an end of the cylinder, the assembly being arranged to provide for effective sealing along the side of the cylinder through which the drive arm projects, and furthermore to provide a sealing structure which is applied under selected tension and maintained through a long time even with normal wear.

Another object is to provide a cylinder of the type described wherein the cylinder portion has a structure facilitating extrusion thereof for ease of manufacture and having a structure which takes up a minimum of space so as to be applicable for use as a window lift in truck cabs or the like.

Yet another object of the invention is to provide a cylinder of the type described having component parts which facilitate easy assembly, disassem bly and maintenance.

The invention will be better understood and additional objects and advantages will become apparent from the following description taken in connection with the accompanying drawings which illustrate a preferred form of the device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view, more or less diagrammatic, illustrating application of the present cylinder in the operation of a window in the cab door of a truck;

FIG. 2 is an enlarged, foreshortened elevational view of the present cylinder taken on the line 2-2 of FIG. 3, a window holding bracket of the structure being omitted for purposes of clarity;

FIG. 3 is a vertical sectional view in reduced scale taken on the line 33 of FIG. 2;

FIG. 4 is a foreshortened sectional view taken on the line 44 of FIG. 2;

FIGS. 5, 6, 7, and 8 are enlarged horizontal sectional views taken on the line 55, 6-6, 77 and 88 of FIG. 3, respectively, these views being turned 90 to the right relative to FIG. 3;

FIG. 9 is a simple diagram illustrating the operating control for the cylinder and piston assembly;

FIG. 10 is an exploded view in perspective showing an end assembly of the cylinder; and

FIG. 11 is an exploded view in perspective showing the components of the piston assembly.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring first to FIG. 1, the fluid cylinder assembly 12 of the present invention is shown mounted inside a truck cab door 14. Such door has a window 16 mounted for sliding up and down movement in a conventional manner, the present cylinder being mounted below the window and having connection to the window and door by means to be described.

The top and bottom ends of the cylinder I2 are provided with ports 18 and 20, respectively, FIGS. 2 and 9, both of which ports are connected by air lines 18a and 20a, respectively, to a suitable control valve 22 of a well known type, by means of which either port can be connected to a source of compressed fluid (not shown) and the other connected to exhaust. A piston assembly designated generally by the numeral 24 is slidable up and down in the cylinder 12.

The cylinder assembly 12 comprises an elongated housing 26, FIGS. 38, which can be readily formed by extrusion and cut to length. The housing 26 has side flanges 28 by means of which it may be secured flatwise to an inner surface of the door 14 in upright position. A wall of the housing 26 has a narrow slot 30 therein which extends longitudinally the full length thereof. This slot accommodates an arm 32 of the piston assembly 24 which extends out from such assembly beyond the cylinder in a slidable arrangement. A thin, semiflexible strip of material 34, preferably metal, FIGS. 2, 3, 5-8, and I0 is disposed on the inside of the housing 26 so as to cover the slot 30 in those areas not occupied by the piston 24, this strip being associated with the piston assembly in a manner to be described hereinafter.

The arm 32 of the piston assembly is integral with a main piston body 36, FIGS. 3, 7 and 11, and extends out through the slot 30 of the housing. The lower end of the main piston body 36 has a reduced dimension projection 38 for supporting a flexible plunger-type cup 40 which has slidable sealing engagement with the inner surface of the housing 26, the projection 38 being provided with a peripheral flange 42 having locking engagement in an aperture 43 in the cup.

For the purpose of holding the piston assembly 24 and therewith the window 16 firmly against any inadvertent downward settling movement when the piston assembly is not being operated, the latter is provided with a spring actuated clutch type brake which will now be described. The main body portion 36 of the piston assembly, as best shown in FIGS. 2, 4, 6 and 11, is formed with a transversely extending slot 44 which as best seen in FIG. 4 decreases in depth from bottom to top. A clutch brake roller 46 is carried transversely in this slot and has a center portion 48 of reduced diameter. A central, longitudinally extending slot 50 crosses the transverse slot 44 and slidably accommodates a roller control bar 52. This control bar has a transverse slot 54 which receives the reduced center portion 48 of the clutch brake roller 46. In the arrangement shown particularly in FIG. 4 by full and phantom lines, movement of the control bar 52 controls the position of the roller 46 in the slot 44.

The control bar 52 has a transverse body portion 56 from which extends a reduced diameter projection 58 arranged to support a flexible plunger-like cup 60 thereon, the projection 58 having an end flange 62 and arranged to have locking engagement in an aperture 64 in the cup 60. Cup 60 has a sealing engagement with the inner surface of the housing 26 in the movements of the piston assembly. A pair of coil springs 68 have their upper ends engaged on round projections 70 on the lower face of the body portion 56 of the roller control bar, and the bottom ends of these springs bear against the top of the piston body 36. These springs normally keep the roller control bar spaced from the main piston body 36, and by keeping such control bar normally in raised position, they hold the clutch brake roller 46 in upper position, namely, in the full line position of FIG. 4, and thus in wedging position between the piston body 36 and the wall of the cylinder housing 26. In such position, the roller 46 prevents downward movement of the piston in the cylinder but permits upward movement of the piston. However, downward pressure on the top of the roller control bar against the force of the springs 68 results in positioning the roller 46 lower down in the slot 44, namely, in the phantom line position of FIG. 4, and out of wedging or clutching engagement between the piston and the cylinder. This permits downward movement of the piston in the cylinder to take place as long as pressure is exerted on the top of the roller control bar 52, whereupon it is apparent that the piston will move up and down when driven by the fluid force but will be locked in position against downward movement when the fluid pressure is removed. Such prevents the window from moving down when there is no fluid pressure. The window however can be raised manually without fluid pressure.

The upper end of the housing 26 is closed by a plug 72 and associated cap 74, FIGS. 24, and 10. Plug 72 fits snugly within the housing, as does a portion of cap 74, the latter member having an end flange 76 which engages the end of the housing and which is secured thereto by a pair of screws 78 arranged to be threadedly engaged in the end of housing aligned with the flanges 28. Cap 74 has a reduced end portion 80 received in a recess 82 in the plug 72. An O-ring 84 is placed on the reduced end portion 80 so as to be disposed between the shoulder 85 formed by the reduced end portion 80 and the end of plug 72. A pair of screws 86 extend through the cap 74 and have threaded engagement with the plug 72 to not only hold the two parts together but also to compress the O-ring and form a positive seal for the housing.

The other or bottom end of the housing 26 is closed by an end plug 720 and cap 74a, FIGS. 2, 3, 4 and 8, the same as described in connection with that described in connection with the top end, the corresponding parts being designated by the same reference numeral but additionally with an a. The bottom end cap 7411, as well as its associated plug 72a, FIGS. 2 and 3, has a longitudinal side groove 88 in which an adjacent end portion of the strip 34 lies, such groove being of substantially the same width as the strip 34 and a depth corresponding to the thickness of the said strip for effective sealing with the O-ring 84a. The strip 34 at this lower end has an aperture 90, and an anchor pin 92 is mounted in the end cap 74a arranged for engagement in the aperture 90 to provide an anchor for one end of the strip.

The end cap 74 at the upper end of the housing 26, FIGS. 3 and 10, has a top groove 96 which starts intermediate the sides of the top surface and leads in a deepening dimension toward the side at which the strip 34 is disposed, the side surface of the cap 74 and plug 72 also having a groove 88 as in the bottom cap 740 and plug 72a for receiving the strip 34. Secured on the end of the cap 74 by means of the screws 78 is a leaf spring lever 100 have a widened body portion 102 for receiving the screws and having a tongue portion 104 an end portion of which is slightly off-set from the plane of the body portion but normally parallel thereto. The end of the strip 34 adjacent to the lever 102 has an aperture 105 arranged to receive an end portion of the tongue 104 of the lever 100. The arrangement is such that in the assembly of this end of the housing the body portion 102 of lever 100 is clamped flat on the end of cap 74 by the screws 78 and the tongue 104 must be bent down in the groove 96 for reception in the aperture 105. By this arrangement, the lever 100 applies a constant tensioning force on the strip 34 even with some wear of the parts, thus maintaining a good sealing disposition with the slot 30.

A channel 106 is provided in the face of the piston assembly for receiving the strip 34, this channel being of suitable dimension to provide a sliding association with the strip. This channel is also provided in the end cups 40 and 60 and also in the flange 56 of the roller control bar 52 and is deepened at 1060 near the mid section of the main piston body 36 to enable the strip 34 to pass beneath a cross bar 360 formed by the deepened portion of the channel. The flexible strip 34 is thus in contact with the wall of the housing along the inside of the slot 30 at all times over the entire length of the slot except at the particular location on the piston where it is diverted inwardly in the mid section of the piston so as to pass under the cross bar 360. A sealing engagement is thus provided along the slot 30 in all places except in the area where the piston is disposed, the said area where the piston is disposed being sealed at the slot by the piston itself. Thus, the piston assembly can move up and down in the housing with effective sealing in the entire housing.

The double acting fluid cylinder is illustrated in FIGS. 1 and 3 as comprising a drive for a truck cab window wherein the arm 32 is engaged in an aperture 107, FIG. 3, of a bracket 108 comprising a window lift bracket having an upper channel portion 110 arranged to receive the door glass 16. Arm 32 is notched top and bottom at 32a for reception in the aperture, such notched portion serving to hold the bracket 108 in spaced relation from the cylinder housing 26 so that it will not rub on the housing.

With reference to FIGS. 2, 3, and 7 a stop 112 is secured to the front wall of the housing 26 adjacent the lower end thereof. This stop has rearwardly extending arms 1 l4 and right angle tabs 116 through which rivets 118 extend to secure the stop to the flange portions 28 of the housing 26. The stop 112 is selectively located to limit the downward movement of the piston as determined by the desired range of travel of such piston. The upward travel of the piston is limited by engagement of such piston with the upper plug 72.

It is preferred that the slot 30 in the cylinder housing 26 have a dust cover, and for this purpose a thin flexible strip 120, FIGS. 2-8, is secured as by adhesive 122 in a longitudinal recess 124 in the outer face of said housing. The strip is slit longitudinally at 126 along the path of travel of arm 32, and such arm moves through such slit with the flexible material of the strip closing and opening closely thereto to keep out dust.

According to the invention, a double acting fluid cylinder is provided which drives through a side of the cylinder rather than through an end piston rod and which by its structure has effective sealing through the side drive opening. Such scaling is accomplished, even though slight wear of the parts occurs, by the tensioning lever 102 operating on the strip 34. The present device by its construction also is readily assembled and disassembled and easily maintained.

It is to be understood that the form of my invention herein shown and described is to be taken as a preferred example of the same and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of my invention, or the scope of the subjoined claims.

Having thus described my invention, 1 claim:

1. A double acting fluid cylinder comprising an elongated cylinder housing having opposite ends, a plug fitted snugly in each end of said housing having an outer end edge and a central recess, a cap disposed at each end of said housing, an end flange on said caps abutted against respective ends of said housing, screw means extending through said flange and engageable with said housing to secure said caps on the housing, a reduced end portion on said caps extending into the recesses of respective plugs, said reduced end portions forming an inwardly directed shoulder on said caps, a resilient seal ing ring between the shoulders of said caps and the outer edges of respective plugs, screw means extending through said caps and engageable with respective plugs for securing the caps and plugs together and also to compress said sealing rings for accomplishing a positive seal between said cap and said housing, a pair of ports located at opposite ends of said housing respectively to serve alternately as inlet and outlet ports, a piston assembly slidably mounted in said cylinder housing, means defining a slot extending longitudinally along one side of said housing, an arm on said piston assembly projecting through said slot and arranged to be connected to means to be driven, a flexible strip extending longitudinally of said housing interiorly thereof covering said slot from the inside and sealing the latter on opposite sides of said piston assembly by internal fluid pressure, means defining a groove in said piston assembly slidably engaging said strip, means anchoring one end of said strip to one of said caps, said strip at its end opposite from the anchored end having an aperture therein, and a leaf spring lever secured at one of its ends to the adjacent cap and having its other end engaged in said aperture, said other end extending toward said strip but normally positioned outwardly from said aperture longitudinally of the housing when not engaged in said aperture whereby said spring is flexed when engaged with said aperture and a tensioning force is exerted and maintained on said strip for positive sealing by said strip.

2. The double acting cylinder of claim 1 wherein said anchoring means includes an anchored end aperture in said strip, and an anchor pin on said housing in hooking engagement with said anchored end aperture to removably hold said strip for tensioning by said leaf spring lever.

3. The double acting cylinder of claim 1 wherein said plugs and caps have longitudinal side grooves to receive said flexible strip, said sealing ring engaging said strip to provide a positive seal at said strip.

4. The double acting cylinder of claim 1 including a flexible dust cover on the exterior of said housing covering said slot and mounted by securement means, said cover having a longitudinal slit through which said arm moves.

t a: t: 

1. A double acting fluid cylinder comprising an elongated cylinder housing having opposite ends, a plug fitted snugly in each end of said housing having an outer end edge and a central recess, a cap disposed at each end of said housing, an end flange on said caps abutted against respective ends of said housing, screw means extending through said flange and engageable with said housing to secure said caps on the housing, a reduced end portion on said caps extending into the recesses of respective plugs, said reduced end portions forming an inwardly directed shoulder on said caps, a resilient sealing ring between the shoulders of said caps and the outer edges of respective plugs, screw means extending through said caps and engageable with respective plugs for securing the caps and plugs together and also to compress said sealing rings for accomplishing a positive seal between said cap and said housing, a pair of ports located at opposite ends of said housing respectively to serve alternately as inlet and outlet ports, a piston assembly slidably mounted in said cylinder housing, means defining a slot extending longitudinally along one side of said housing, an arm on said piston assembly projecting through said slot and arranged to be connected to means to be driven, a flexible strip extending longitudinally of said housing interiorly thereof covering said slot from the inside and sealing the latter on opposite sides of said piston assembly by internal fluid pressure, means defining a groove in said piston assembly slidably engaging said strip, means anchoring one end of said strip to one of said caps, said strip at its end opposite from the anchored end having an aperture therein, and a leaf spring lever secured at one of its ends to the adjacent cap and having its other end engaged in said aperture, said other end extending toward said strip but normally positioned outwardly from said aperture longitudinally of the housing when not engaged in said aperture whereby said spring is flexed when engaged with said aperture and a tensioning force is exerted and maintained on said strip for positive sealing by said strip.
 2. The double acting cylinder of claim 1 wherein said anchoring means includes an anchored end aperture in said strip, and an anchor pin on said housing in hooking engagement with said anchored end aperture to removably hold said strip for tensioning by said leaf spring lever.
 3. The double acting cylinder of claim 1 wherein said plugs and caps have longitudinal side grooves to receive said flexible strip, said sealing ring engaging said strip to provide a positive seal at said strip.
 4. The double acting cylinder of claim 1 including a flexible dust cover on the exterior of said housing covering said slot and mounted by securement means, said cover having a longitudinal slit through which said arm moves. 